Z01 HD 01123-09 LCE and Z01 HD 01124-09 LCE are companion projects that together investigate auditory communication in primates from receptors to the rainforest. The overall goal of these studies is to provide a comprehensive understanding of primate auditory communication in terms of development, neural mechanisms, related endocrine factors, and social context. Two non-human primate species, the squirrel monkey and the common marmoset, are the main subjects of study, with additional data collected in collaborative studies from a wider range of species including rhesus macaques and humans. Prior work in this project has shown that production of sounds of non-human primates that are the functional and structural equivalents of crying in humans is mediated by transitional cortex located along the anterior midline of the cerebral cortex, and that single neural elements in the auditory cortex (superior temporal gyrus) are particularly responsive to subtle differences in the acoustic structure of species-specific vocalizations, suggesting an important role in mediating individual differences (vocal signatures).New findings in FY99 were (a) lesions of the inferior temporal cortex in rhesus macaque neonates results in altered vocal behavior that is evident as early as 1 month of life and persists at least into the second year; (b) prolactin levels in common marmosets were significantly correlated with carrying time in infant retrieval tests, and the dopamine agonist bromocryptine reduced serum levels of prolactin and significantly increased the mean latency to retrieve infants; (c) adult common marmosets with experimental autoimmune encephalitis (EAE) as a primate model for studying multiple sclerosis (MS) produced characteristic phee vocalizations that differed in several parameters from phee calls made by these same animals prior to EAE-induction. - primates, vocalization, brain, neuroethology